Years ago I went to a concert by a group called Hiroshima (pronounced Hero Sheema). They played western music (as well as traditional music) on traditional Japanese instruments. The koto player did things similar to that video as well as popular ‘80s music. I was enthralled!

Are you sure? The YouTube videos say Luna Lee's playing a gayageum, which is a traditional Korean instrument, according to Wikipedia.

Basically the same instrument. The Koto can have any number of strings just as its Korean relative, be different sizes, and both use variable tunings (most traditionally pentatonic,) and are played with the same technique. Without drawing too fine a line, it's sort of like the difference between an upright piano and a grand piano. Both are played on keyboards, tuned the same way, etc., etc. 'A rose by any other name...'